Jepps Lewis, Briskham Paul, Sims Neil, Susmel Luca
Department of Civil and Structural Engineering, University of Sheffield, Sheffield S1 3JD, UK.
Atlas Copco, Deeside CH5 2NS, UK.
Materials (Basel). 2023 Mar 29;16(7):2747. doi: 10.3390/ma16072747.
During the design of automotive structures assembled using Self-Piercing Rivets (SPRs), a rivet and die combination is selected for each joint stack. To conduct extensive physical tensile testing on every joint combination to determine the range of strength achieved by each rivet-die combination, a great deal of lab technician time and substrate material are required. It is much simpler and less material-consuming to select the rivet and die solution by examining the cross sections of joints. However, the current methods of measuring cross sections by measuring the amount of mechanical interlock in a linear X-Y direction, achieved with the flared rivet tail, do not give an accurate prediction of joint strength, because they do not measure the full amount of material that must be defeated to pull the rivet tail out of the bottom sheet. The X-Y linear interlock measurement approach also makes it difficult to rapidly rank joint solutions, as it creates two values for each cross section rather than a single value. This study investigates an innovative new measurement method developed by the authors called Volumelock. The approach measures the volume of material that must be defeated to pull out the rivet. Creating a single measurement value for each rivet-die combination makes it much easier to compare different rivet and die solutions; to identify solutions that work well across a number of different stacks; to aid the grouping of stacks on one setter for low-volume line; and to select the strongest solutions for a high-volume line where only one or two different stacks are made by each setter. The joint stack results in this paper indicate that there is a good predictive relationship between the new Volumelock method and peel strength, measured by physical cross-tension testing. In this study, the Volumelock approach predicted the peel strength within a 5% error margin.
在设计使用自冲铆接（SPR）组装的汽车结构时，要为每个接头组合选择铆钉和凹模的组合。若要对每个接头组合进行广泛的物理拉伸测试，以确定每种铆钉 - 凹模组合所能达到的强度范围，则需要大量实验室技术人员的时间和基材。通过检查接头的横截面来选择铆钉和凹模解决方案要简单得多，且耗材更少。然而，当前通过测量扩口铆钉尾部在X - Y线性方向上的机械互锁量来测量横截面的方法，并不能准确预测接头强度，因为它们没有测量将铆钉尾部从底层板材中拔出时必须克服的全部材料量。X - Y线性互锁测量方法还使得难以快速对接头解决方案进行排名，因为它为每个横截面生成两个值而非单个值。本文作者开发了一种名为体积锁（Volumelock）的创新测量方法。该方法测量将铆钉拔出时必须克服的材料体积。为每种铆钉 - 凹模组合创建单个测量值，使得比较不同的铆钉和凹模解决方案、识别在多种不同接头组合中都适用的解决方案、帮助在低产量生产线中将接头组合分组到一个安装器上以及为高产量生产线选择最强解决方案（其中每个安装器仅制造一两种不同的接头组合）变得更加容易。本文中的接头组合结果表明，新的体积锁方法与通过物理十字拉伸测试测量的剥离强度之间存在良好的预测关系。在本研究中，体积锁方法预测的剥离强度误差幅度在5%以内。
